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How to determine the condition of bearings in a 10ee, and other questions


Hot Rolled
Feb 17, 2008
You mean my lathe ISN'T supposed to be this loud???

I made the mistake of watching a You Tube video of a more modern 10ee, and it was just so dang quiet! Mine makes all kinds of racket, but has since the day I've owned it, so I didn't really know any better. I've spent a fair amount of time trying to improve the condition of the lathe, but in the last few years I've mostly just used it.

So after finishing up some tube bending work this weekend, I decided I had enough time to take the belts off and poke around.

The machine is loud. It's a '54 MG, and I use an RPC to power it. The MG seems to work fine, and other than the jet engine sound, sounds reasonably healthy. On shut off, it takes forever to slow down, though there is quiet underlying high pitched noise as it slows down - not something I've been too concerned about.

However when the spindle is on, there is a noise that I've never been able to put my finger on. It's loud, but I couldn't tell you what it sounded like, exactly. It doesn't change when the feedscrew or leadscrew are activated, so it doesn't appear to be gear train related. I pulled the flat belt (which needs replacing, apparently), and there was no apparent change in sound (not surprisingly, as gear train previously didn't appear to be involved). I pulled one of the v-belts, which made no difference in sound. So I pulled the last one. When just the DC motor/backgear is running, there is a lot of noise from that apparatus. I would liken it a little bit to the sound of a twin screw supercharger. But while a supercharger sounds cool, this sounds, ehhhhhh not cool. Just LOUD. So I pulled the backgear box, and ran the motor without the backgear, and it is more quiet, but there are still rhythmic noises.

While I was at it, I hand spun the spindle. The spindle spins without any outwardly bad sounds, and will rotate several revolutions before stopping. BUT - it does not feel glass smooth, like a well adjusted plain bearing. It doesn't have any discernible bad regions, and it doesn't feel what I would call gritty, but when spun, it does make an audible sound - it's a light noise. I would also say that I can feel the noise through the headstock when I put my hand on the lathe. It's not much, but if I were stone deaf, I'd be able to pick it up. I haven't put an indicator on it, but the spindle doesn't feel loose, or feel like it shifts when wiggled (for what that's worth, which is next to nothing).

So I think the lathe is noisy because of an accumulation of vibrations from multiple sources. My main concern isn't the noise per se - I've used it this way for years to satisfaction. My concern is that perhaps there are multiple issues that need to be addressed, and I want to know what is a real problem, and what is just to be taken for granted in a machine that turned 60 this year.

Question 1) Based off of my crummy description, does the spindle bearing noise describe bearings in workable shape, or is should they feel like glass and have no sound? If they need work, is there any way to determine whether it is the front or back, without taking the spindle apart? I have never dissembled the spindle in this machine, but I do have the Monarch manual for the machine (purchased from Monarch). I'm not sure if it's a real pain to pull the spindle and the bearings. If this were a reasonable task, could a bearing shop determine the real condition of the bearings?

Question series 2) The next area that really needs attention in my mind is the backgear. I cracked open the box, and found that the dog clutch has some definite signs of slippage. The clutch half attached to the large bull gear appears in decent enough condition (as makes sense as I've read that this is of harder stock I believe?), but the mating half is pretty rough. It probably has some life left, but does anyone have a donor, or have any suggestions for refurbishment? I spent about 8 years as a professional welder (whatever that means...), but I'm not sure how I'd reshape the dogs once built up (if it were weldable), due to the inside corners. If the dog clutch slid off the rest of the part, I could almost see it, (though it would take some figuring). Some of the gears have leading edges that show signs of being roughed up by some of the other gears - perhaps a little whiskey got left in the gear box one night and they started a fight? Could these roughened edges contribute to excess noise, or is this unlikely? Again, similar to the spindle bearings, the big output shaft bearing feels ok but not glass smooth, but when spun, makes some audible noise. Is this in need of replacing?

Question series 3) The motor contributes to some of the noise, I'm sure. It doesn't seem to have any glaring issues, but I am starting to wonder if there is a slight eccentricity to the commutator. As I understand it, if I take the front of the motor housing off, I can slide the armature out, and then the commutator portion can be turned true? If I did that, are the front and rear motor bearings reasonable to either check or replace? I'm assuming those guys wouldn't be prohibitively expensive - I know the spindle bearings are pricey, though I'd probably spring for them if I had to - still cheaper than a new lathe of this quality! As a side note, the motor will make a little buzzey sound that is seemingly random and not very loud - I imagine it might possibly be the sound of a loose bearing buzzing on a shaft. Maybe there are other motor elements that might make this sound? The brush timing is good, and there is no visible arcing at any point. A couple of years ago or so I dealt with that, and it's been fine ever since then.

I realize this is a terribly long post. I'm collecting my own thoughts here as I write. I'd appreciate any feedback from you fine gents.
Oh - I didn't mention this before, but I was wondering if the v-belts are telegraphing a lot of the noise from the gearbox to the spindle - I don't know if they do that.
Problems with the spindle bearings will show up first in poor surface finish. If the surface finish is adequate for YOUR needs, leave the spindle bearings alone.

You've definitely got issues with the spindle motor and back-gear unit, so start there. You're pretty far into it already, so it's a good time to replace the motor's bearings and brushes, and true the commutator with a commutator stone. (There's no need to turn the commutator unless it's in really bad shape.)

If you got the skills, go ahead and try welding up the clutch dogs. Use high spot blue to make sure that you have good contact in all possible engagements of the clutch dogs and you're good to go. Replace the back gear bearings and see where you're at. None of the bearings for the motor or back-gear are terribly expensive.

Check/replace the bearings in the belt idler(s). The V-belts need to be the right type, intended to be use in multiple belt applications; if you're running the wrong belts, it can cause noise and surface finish problems.

Thanks Cal. Regarding the clutch dogs, should they fit with little play? As they are now, there is a decent space (I'll go out and measure later) between mating teeth, such that they can rotate several degrees relative to each other. I was starting to consider machining a replacement setup, as a 2 -piece part one part consisting of one half of the dog clutch, one part the gear and shaft, then silver braze it together. That would require a lathe that's put together, but I could measure, reassemble, machine, disassemble, and then replace the part again. That sounds like a lot of effort, now that I type that out! If the play between teeth isn't an issue, I could just weld it up so the faces are square and call it good. I am curious how they fit together when new.
I cracked the motor apart in place tonight. Boy, the front bearing for the DC motor feels really smooth, though will allow for some movement when rocking it forward and back. I don't know my bearings well enough to know whether this is ok or not, but I suspect that the design of that bearing allows for that. In trying to pull the armature, it's still firmly connect to the back of the motor. I'd prefer not to remove the motor housing, as 1) it's heavy and 2) I don't want to disturb wires I don't have to. I know that the wiring insulation is getting on in years. Is there any chance of pulling the armature out without pulling the motor? If so, any tips/tricks to doing that? I thought about making a crude puller using a piece of wood or metal scrap with 3 holes drilled in it: 1 big hole for the armature shaft, an 2 threaded holes to push on the motor housing. I'd then have to put a shaft collar on in front of the wood to give the wood something to push off of. Hmm - maybe that would work... Because the bearings feel smooth as they are now, it makes me wonder if the noise that I heard associated with the motor was something related to the brushes, and not the bearings. My elbows are in this far, seems a shame to just bolt the motor back up.

I realized that the dog clutch half in the gearbox IS a two piece job. That makes me think it would almost be easier to just machine that part. I wish I knew what the fit was supposed to be like for that part - whether it was supposed to have .050"+ slop in the clutch teeth, or whether mine is just REALLY worn. On the other hand, welding the teeth up so that they have a flat edge (instead of bread loaf shaped), maybe using copper as a heatsink/backstop to help form the flats (then cleaning up with a file, etc) would be as good, or better. One concern is that if the fit isn't nice and tight, that it might contribute noise to the system due to the dogs hammering on each other. Is that unfounded?
Just my two pennies.. If you have a mill you can use it for a lathe. If the shaft is short, stand it up in the vise with a V block. If it's long, stand it up with a knee off the side of the table. Use a boring head with the bar turned 180 degrees from usual and back bore the OD. For me when I've had to build up something with weld and file fit it back, roughing it in even by free handing with the mill I do a much better job! Good luck any double E is nice, but a nice double E pleasure!!
I'm not sure what the clearance on the dog clutches should be, but a few degrees of lash doesn't sound unreasonable. DaveE907 posted on the rebuild of his backgear, but I can't find the post. I pinged him to see if he can help.

There are only four wires connecting the spindle motor to the DC control box. Take the wires from the DC control box loose at the terminal box (aka peckerhead) on the side of motor, disconnect the conduit and you can remove the motor. If there's any problem with the wires to the DC box, they are easy to replace, but don't mess with the wiring to the motor windings themselves unless you want to turn the motor into scrap. Make a plywood platform next to the base (or use a 4-wheel furniture dolly) and you can drag the motor out where you can work on it. The motor with backgear weighs about 300 pounds; it's not so heavy that one guy can't drag it around on the floor (lifting is entirely another matter).

If you're going to pull the armature, definitely replace the bearings; they're not that expensive. Bearings can feel smooth by hand and still be shot.

My memory tells me there is clearance between the dogs, .050 is a good guess, Since there is so little wear on the dogs in the reverse direction, that would be the profile to match you weld job to.

When turning the spindle without belt, chuck a piece of stock in the chuck, the jaws clack a bit after a decade of use. Also check the feed lever position when hand turning, make sure its not in threading position, nor any others in threading mode. And the tach drive is geared off the spindle, I doubt those little gears could be heard or felt but maybe.

The output shaft bearings in the gearbox may be $$ as they are angular contact bearings. They do get subjected to the metal chips in the oil worn off the gear teeth over the last 60 years.
I rebuilt my back gear on my 1952 10EE some years back. Some of the details are fuzzy now.

My sliding dog clutch was in rough shape and I momentarily considered TIG welding the teeth too. Welding on mystery metal and putting the repair inside a hard to replace gearbox with possible impact loads on the welds gave me pause. The part is simple however and I felt a more reliable repair was to make a new one. I disassembled it from the sliding gear, measured it and made a new one from 4130 PH. There is clearance between the mated dog clutches but I can't recall how much. Unless yours is completely rounded off there will be enough residual face of the original dogs to measure it. As I recall it was just a mirror image of its much harder mating clutch integral to the bull gear on the output shaft. I looked but can't find the drawing I made for the new part. It was easy to make, the only close tolerance was the bore. I likely tossed the drawing as I knew I'd never have to make another one.

It's obvious Monarch designed that part to be the replaceable part compared to its far more expensive mate on the output. It's 15-20 down on the Rc scale and a simple slide on part with setscrews. Their engineering is still enthralling many decades later. They knew untrained would be running their products.

The back gear jack shaft bearings are a common size and inexpensive, as recommended, replace them. As Tom mentioned the output bearing is another matter, they are expensive and the way it's installed there is no way to remove it without destroying it. I kept my original, it was still in good shape. My 10EE had low hours on it but the dog clutch had been mistreated along the way.

Remove the motor to work on it. Always. Do you know if letting the armature drop to the field when pulling the end didn't take the back bearing beyond it's angular limit and ruin it? That motor was at the peak of technology years ago. I use a dedicated modified furniture dolly to move the motor and MG out of and into my 10EE. It's deck is slick sheet metal shimmed to the same height as the bottom deck of the base casting. I'm old and can do it alone with that dolly.

To answer some questions: clearance between the dogs is not critical. There are no torque reversals across the clutch during normal operation. They aren't making noise. Your motor bearing rocking slightly side to side is normal, the rhythmic sound you heard is not. Very likely it's the bearings. If original and unmaintained the grease turns into something far from it, the bearings suffer. Manually handling a ball bearing will only identify very gross failures with lubricant present. You can't get in there with a microscope to check it out. Replace when in doubt if they're inexpensive is always the best route.

Good luck!
Thanks for the info, guys. Based on your suggestions, I went ahead and pulled the motor. You are right - it wasn't too bad. I decided to just muscle it by hand to the floor, as I've got narrow working quarters at that end (there's another lathe and some other junk back there), and that wasn't too much trouble. It is a pretty heavy motor, I'll say that. Funny to think that it's a 3 hp motor (granted a STRONG 3HP), but it seems to weight about as much as a small car motor with 20X the HP! That actually might make for a fun spindle motor - a little VW diesel or some such. Might be quieter too (kidding of course).

I'll hopefully get the back of the motor cracked apart tonight, and take the bearings in to the supply house here (McGuire Bearing). I may also check ebay, I suppose, thought I'd rather get it bolted back up sooner, if the bearings aren't too expensive in the first place.

On the plus side of pulling the motor all the way out, I can clean the huge amount of sludge that has built up in here. I have a feeling the oils were just drained into the machine for changing. It does leak internally a little too, but man there is a lot of SLUDGE in here... Nothing new I suppose.

I'll try and submit some photos of progress sometime. I'm pretty lazy about that sort of thing, and I know you guys have seen the inside of a 10ee before (clearly)! Still, it's always fun to see other people's machines.

I feel like a garden gnome should be posted as lookout inside the machine for some reason. Is that weird?
Ok, so I cracked the motor apart - no big deal. It's a good thing I didn't try to pull the spindle out without removing the motor, as the back bearing is attached to the armature shaft with a locknut! That would have been frustrating, to say the least. The bearings required a little heat to pop off the shaft - they did feel smooth, but from Dave's description that doesn't mean a whole lot. I now feel like I'd like to take a class in bearing mechanics. I'm realizing that my knowledge of bearings is shamefully minute.

Speaking of which, I've started cataloging some of the bearings I will be needing. I think that I'll just go to the bearing shop for the motor bearings, so i can get the motor back together and clean up the lathe cavity (which is feeling more and more like the inside of a thanksgiving turkey, with me as the stuffing). The gearbox, I'd like to take a little more time with possibly. I'm intrigued with the possibility of substituting the 20209 output bearings with the snap ring for the 6209-N bearing that RC99 mentions here:


From the drawing, I can see that there are 2 bearings. I also understand that removal of the bearing becomes destructive, though I don't fully understand why. But then, I also don't quite understand how I get the bullgear attached the the bearings off either, so maybe it's related to that. Anyhow, if I replace the output bearings with the 6209-N bearings, I don't know if there is anything that needs to be considered. Is this a direct drop-in replacement? These seem possibly more available and lower priced than the 20209 with groove? The other question is: Do I only need one with the groove? Or is there a need for both to be grooved?

Also along these lines, what is a good way of removing the bull gear from the bearing, if I were to replace the output bearing? I'd like to remove the bull gear so that I can more easily file the deformities. If the bearing replacement is prohibitively expensive (I'm not sure yet what that would be), and I'd be endangering the bearing by removing the bull gear, I'll leave well enough alone.

Thanks for your help.
Also take the armature and yoke to a motor shop and have them meggared - ideally - otherwise you can do at home with a good VOM - if you get 1 megohm or more you are good to go. Motor shop may also be a good idea to have them look for open / shorted coils.

Make sure the mica insulation between each commutator segment is below the commutator surface. Quick n dirty test is to see if bar edges catch a fingernail. IF you need to undercut the mica you can do with hacksaw blade ground to with of gap between bars - depth of 1/64 to 1/32 should suffice. Bevel the edges of each bar after undercut. You do not want the brushes bouncing -- may be good to check run out with dial indicator.

Dan Bentler
Regarding the gnome: Aha - well, I'm glad I didn't get caught with my pants down on THAT one! That would have been quite the embarrassment for sure. I'll just go put that back in the neighbors yard then...

Good to note about replacing the brushes, commutator cleanup, etc. I did the brush timing in place by the seat of the pants last time, and it was pretty good, but I might be able to make it better, and having it out of the chamber would definitely make it easier. I'll think about that one too.

I'm definitely not ready to give up on the MG set yet, but the Beel drives sure do seem interesting. I know they've been discussed a few times.
Oh hell - I see there's old posts that I missed regarding some of my questions. Sorry guys. Still feel welcome to chime in on any topic, but I feel bad for asking some questions I see have been answered several times. I just need to dig a little better.
You need a tool known variously as a "bearing separator" and also as a "bearing splitter" to remove the bearings from the output shaft in one piece. Just plug either name into your favorite search engine and go to images to see what they look like. The operation is pretty obvious by inspection, it forces opposing semicircular wedges between the bearing outer race and the shoulder it is up against to force the bearing off. Once it bottoms either the bearing is off or there will be a large enough gap to do normal press work to finish the job.

The loads it applies across the balls is its disadvantage. It directly loads the bearing with high axial forces between the inner and outer races across the balls to overcome the press fit between the shaft and bearing inner race. The forces very often are high enough to ruin the bearing by permanently deforming the balls and/or the races. That's why it's regarded as a destructive method but in a circumstance such as the output shaft the best option other than breaking or cutting the races. That's another way to do it when a bearing separator isn't available.

Most automotive machine shops are well equipped to do the job if one doesn't want to tackle it.
Some photos of the machine in question before pulling it apart.

A few months ago, I tuned up the cross slide and compound. This machine is a bit of a mish-mash - the compound is from an older machine, and the bed and saddle I bought from Monarch several years ago, as the originals were utterly trashed. Part way though scraping the compound rest.

The 10ee is to the lower right in the picture.

Working. The thing sticking out the back of the spindle is a spindle stop I made recently for repeat parts, based on a simple, but very effective design.
Alright - here's some photos of the drive system parts taken apart:

That doesn't look quite right!

Believe it or not, it used to be WORSE! I've actually scooped a lot of crud out previously.

Well I'll be danged - I had no idea it was that color.

Green? I thought it was black. Seriously.

I've seen man hole covers that had less material in them. Compared to other electric motors I've seen (which isn't saying much), these just seem ridiculously built (in a good way).

I've ordered bearings for the front and rear of the motor, as well as for the backgear unit. I'm hoping that the pair of Nachi 6209-2NSE9NR bearings I purchased will substitute for the New Departure 20209 bearings for the backgear unit output. I'll get a bearing splitter sometime soon, and pull the rest of the backgear apart. My plan is to hand file the gears back into shape - I think they are still serviceable, just a little mashed at the edges. Because they have raised sections at the periphery, I'm hoping that they are what is contributing to the noisy gearbox. I'd really like this process to result in a quieter machine. In any event, I'll still feel that the work is worth it, even if it doesn't quiet it down.

The dog clutch part I'm waffling on. It does need a keyway cut in it, and I have no broaching equipment, nor a shaper (though a friend recently purchased an FP1, including a shaping head). I could take it somewhere to be cut I suppose. I could measure it, put it back together with the original part, then do the lathe work for a replacement, machine the dog teeth, then bust the backgear open again, and install it, but that feels a little silly. I could machine the replacement, and then just leave the unit as is until I start having issues with the clutch, and then replace it alternatively. The warning about welding the teeth, and then filing or machining them back to shape has resonated with me - I'm taking that warning seriously. At the same time, I wonder how likely the material is to be something that would not take nicely to welding, such as a leaded steel. The part itself is good, save for the wear, and that bore fits so tight on the shaft, I wonder if I'd be able to get such a nice fit and smooth bore without grinding. I guess it's a bit silly to worry about that - I could make it work without it being as perfect as a factory Monarch part.

I am starting to consider replacing the back bearings in the spindle as well - probably at a future date. I still need to do some research here to determine whether I'm likely to mess up the front bearings though. I'd buy replacements if absolutely necessary, but would rather not. I get this gut feeling that the little bit of vibration is coming from back there, and not the front, though that is just pure speculation. I'll see how everything seems with this series of repairs. I've also got a replacement Bison chuck for the Buck 6-jaw that is a little long in the tooth. It works, but is getting sloppy. It also doesn't have reversible jaws, so on occasion I run into workholding difficulties with larger parts. I might feel satisfied for awhile having dealt with this. The surface finish isn't anything I'd complain about, but it eats at me thinking that the spindle could be glass smooth when its not.
Hey Bill, thanks for the perspective. Good points. I guess I would hate to end up causing wonton destruction inside of the reduction unit (better term?) due to my own ignorance. I'm willing to take some risk to perform the repair - I just want the risk to be relatively low. If I had a 50/50 chance of the repair actually causing more damage than just being left alone, well, I'd feel even dumber than I already am. But, that repair you mentioned gives me something to reference - I'll search for that.

As to the bed and saddle and all that, I have had to do some scrape fitting. I bought the used (but in good shape) parts from Monarch, and paid a decent price to have them shipped out to me. Monarch hadn't done work to the bed and saddle as far as I know, and I don't know for fact that they even went together, originally. The did seem alright, but I did a novice job of checking the fit, and putting it all back together. As I recall, I tried to touch up the saddle a little bit. I've definitely worked on the cross-slide, and it's still not up to the standards of many around here, but it's smooth, and holds steady. I have a stack of shims so that the topslide gib fits, and I'd like to do something better someday. It was a big project for me at the time, and I knew quite a bit less about machines then than I do now, which isn't even a quarter of what most of the people on here know, so that's not saying much. That said, I did my best with the time I had, and the machine has certainly helped make money for me, as well as delivered much enjoyment. I tend to come back around and try to do a better job of what I had once done, so I'll some day revisit the fitment of the saddle and bed, and headstock and tailstock. Round in circles we go. Because little of what I typically do REQUIRES extreme precision, I tend to tackle maintenance/improvement a little at a time. When I'm really out of my depth, as is the case with machine rebuilding, I'm fairly tenuous (probably too much so). I should try to find what the machine looked like when I bought it though - it was B A D. I still loved it the moment that I saw it though!

Regarding your suggestion of spinning the spindle up, and then listening, I tried a primitive version of that. I put a rag on the end of the spindle, and then stuffed the chuck of my cordless drill against it, and ran it up and let it go. The RPMs were pretty low, so I didn't get a lot of extra rotations, but I thought it seemed like the noise was more towards the back of the headstock (away from the chuck). I think a stethoscope might improve that determination though. And I didn't mention this earlier, but I'm pretty much always wrong whenever I think I know what's going on with something. Especially my wife. Any thoughts on whether it is fairly safe to pull the spindle far enough out to replace the rear bearings without risking damage to the front bearings? I've started doing a little research through the archives here, but haven't found the exact story I'm looking for yet. Largely because I keep getting side tracked with all the interesting search returns unrelated to what I'm looking for. I know, boo-hoo!
They are not rocket insemination to refurbish

HA! That's a new one to me.

Thanks for the direction. I believe I've run across some of these in the past - but sometimes it's hard for me to remember that I have until I've seen them. Then I go "oh yeah - that's right..." I've a bad memory for certain types of details.

Thanks again Bill (and others). Your help and advice is much appreciated, and none of it goes unconsidered.